Abstract

Objective: This study was planned to detect methicillin resistance in Staphylococcus aureus strains by conventional phenotypic methods and polymerase chain reaction for mecA gene and to compare the results of these tests for their sensitivity and specificity.

Methods: Eighty six methicillin-resistant S. aureus (MRSA) and 30 methicillin-sensitive S. aureus (MSSA) strains from various clinical samples were included in this study. Methicillin resistance was detected by oxacillin and cefoxitin disk diffusion method. Presence of colonies on MRSA chromogenic agar was looked for methicillin resistance. The presence of the mecA gene investigated by polymerase chain reaction is considered to be the gold standard test, and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated accordingly.

Results: The percentage of sensitivity, specificity, PPV and NPV were 98.7%, 81.6%, 91.7%, 96.9% for the cefoxitin disk diffusion test, respectively; 100%, 78.9%, 90.7%, 100% for the oxacillin disk diffusion test, respectively; 45.8%, 63.2%, 70.2%, 38.0% for the 24-hour evaluation MRSA chromogenic agar, respectively; 51.4%, 63.2%, 72.5%, 40.7% for the 48-hour evaluation, respectively.

Conclusions: Investigation of mecA is crucial for taking the necessary precautions in hospitals where the MRSA is a common problem. The results for cefoxitin and oxacillin disk diffusion method were found close to each other; hence, we think that oxacillin disk can be an alternative instead of cefoxitin disk. Results based on chromogenic agar should be interpreted with caution

Cite this article as: Hancı H, Ayyıldız A, Baltacı MÖ, İgan H, Uyanık MH, Adıgüzel A. [Detection of methicillin resistance in Staphylococcus aureus isolates by classical and molecular methods]. Klimik Derg. 2018; 31(1): 30-3. Turkish.